The kinetic sintering of Ni and Al nanoparticles is considered using molecular dynamics simulations. We report on the effects of nanoparticle size on sintering temperature and time, with results showing that surface energy has a slight effect on both results. The effect of surface energy on combustion temperature is limited to nanoparticles of less than 10 nm in diameter. An analysis of the various alloys formed during sintering gives insight into the reaction process. The formation of Al-rich compounds is observed initially with a final equilibration and rapid formation of the eutectic alloy immediately preceded by melting of the Ni nanoparticle. We have observed that nanoparticle size and surface energy are both important factors in determining the adiabatic reaction temperature for this material system at nanoparticle sizes of less than 10 nm in diameter.